text: Cyclohexane is a prototype for low-energy degenerate ring flipping. Two H NMR signals should be observed in principle, corresponding to axial and equatorial protons. However, due to the cyclohexane chair flip, only one signal is seen for a solution of cyclohexane at room temperature, as the axial and equatorial proton rapidly interconvert relative to the NMR time scale. The coalescence temperature at 60 MHz is ca. –60 °C. As a consequence of the chair flip, the axially-substituted and equatorially-substituted conformers of a molecule like chlorocyclohexane cannot be isolated at room temperature.   
  However, in some cases, the isolation of individual conformers of substituted cyclohexane derivatives has been achieved at low temperatures (–150 °C).
  Most compounds with nonplanar rings engage in degenerate ring flipping.  One well-studied example is titanocene pentasulfide, where the inversion barrier is high relative to cyclohexane's. Hexamethylcyclotrisiloxane on the other hand is subject to a very low barrier.
  Bicycloalkanes are alkanes containing two rings that are connected to each other by sharing two carbon atoms. Orientation within bicycloalkanes is dependent on the cis or trans orientation of the hydrogen shared by the different rings instead of the methyl groups present in the rings.
  Tetrodotoxin is one of the world's most potent toxins. It is made up of multiple six member rings set in chair conformations, with each ring but one containing an atom other than carbon.